It is quite well known in the art to provide inserts in bowling ball finger gripping holes. Such inserts are employed mainly for adjusting the effective diameter of the finger gripping holes. It is important to provide the proper finger gripping hole diameter since this contributes greatly to accurate control of the ball. Also, the thumb and fingers should move smoothly in and out of their respective holes, and there should be no excess frictional drag on the thumb and fingers as they leave said holes.
Where inserts are not employed, it has been necessary for bowling alleys to provide a large supply of bowling balls with different hole sizes to accommodate the fingers and thumbs of the various patrons. Individuals who bowl frequently usually buy their own bowling balls and have the holes drilled to conform to their finger sizes. However, where an individual has done this, changes may occur in the finger sizes of the individual either as a result of growth or for other physical reasons. Therefore there is a need for providing changeable inserts as a means for conveniently adjusting the sizes of the gripping holes in bowling balls. With the inserts employed in the prior art, relatively complex and expensive means for fastening the inserts in the bowling balls and relatively complicated hole configurations are required for receiving said inserts. Therefore there is also a need for simplifying the fastening means and the required hole configurations.
A preliminary search of the patented prior art revealed the following U.S. patents, which appear to show the present state of the art:
Bendelari, U.S. Pat. No. 1,026,069 PA1 Darby, U.S. Pat. No. 2,210,528 PA1 Keith, U.S. Pat. No. 2,372,959 PA1 Seurynck, U.S. Pat. No. 2,435,327 PA1 Seurynck, U.S. Pat. No. 2,436,976 PA1 Keith, U.S. Pat. No. 2,872,367 PA1 Insetta, U.S. Pat. No. 3,001,793 PA1 Bunk et al, U.S. Pat. No. 3,012,783 PA1 Jarus, U.S. Pat. No. 3,102,725 PA1 Bednash, U.S. Pat. No. 3,129,002 PA1 Blood, U.S. Pat. No. 3,204,960 PA1 Mason, U.S. Pat. No. 3,239,223 PA1 Gerlach, U.S. Pat. No. 3,393,910 PA1 Ginder, U.S. Pat. No. 3,416,796